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Our future, our universe, and other weighty topics

Thursday, October 23, 2014

Why the “Celtic Cross” on Mars Cannot Be Debunked as a “Screw Imprint”

There has been a very strange
series of unusual things found in photographs taken by unmanned
robots on the planet Mars. Recently yet another strange object was
noticed on Mars. It was described in the press as a “Celtic cross,”
although it does not actually seem to be a Christian cross, in that
the two intersecting lines are the same size. It is more accurately
described as an X shape surrounded by a circle. The image taken on
Mars is below:

Image Credit: NASA

The photograph above was
taken by the Opportunity rover, one of the two robotic rovers now on
Mars. The NASA web page giving the photo says it was taken on Sol
3720, which corresponds to July 11, 2014.

If you do a Google search for
“Celtic cross on Mars,” you will find quite a few Internet
discussions about this photo. At first sight the picture seems to
indicate something sensational – what looks like an image of
something artificial on the surface of Mars, perhaps some artifact
from long ago.

But almost as soon as the
strange shape was discovered, skeptics came up with an explanation
trying to explain it away. The explanation was that the “X within a
circle” or “Celtic cross” shape was a screw imprint. It seems
there is a scientific instrument on the Opportunity rover called the
APXS, which stands for Alpha
Particle X-Ray Spectrometer. On this NASA page, the APXS is described
as a “contact” instrument, leading one to assume that it makes
contact with the soil or rock it is analyzing. The APXS is shown
below:

The APXS instrument

Now here is the ingenious
explanation of the skeptics. They noticed that in the image above,
there are exterior flat screws, which have an “X within a circle”
shape similar to the “Celtic cross” shape discovered on Mars. The
skeptics then suggested that the “Celtic cross” shape was caused
by a “screw imprint” when the APXS instrument made contact with
the surface of the planet Mars.

Some initial visual analysis
leads one to be doubtful about this explanation. The APXS instrument
has quite a few screws that might make an imprint, but we see only
one “X within a circle” in the Mars image of the “Celtic
cross.” Also, there seems to be a kind of handle shape attached to
this “Celtic cross,” something that is not explained by the
“screw imprint” hypothesis. Also, the “X” part of the “Celtic
cross” appears to be higher than the nearby rock or soil, an effect
one would not see if the shape was produced by a screw imprint.

The real test of the “screw
imprint” hypothesis is the timing of the Opportunity rover's
activities. In order for this explanation to hold up, it would have
to have been that the Opportunity rover was actually using the APXS
instrument at the particular spot that the photo was taken, before or
during the Martian day of July 11, 2014 (3720) when the photo was
taken. What do the NASA logs say about this?

The relevant log is found
here, which covers the period between July 9th and July
17th. Below is a screen shot from the NASA web page:

According to the log, between
July 9th and July 17th, the Opportunity rover
was mainly busy traveling. During this period, there was only one day
when the APSX instrument was used for in-place “contact” science:

The one sol of in-situ
(contact) science was the first sol of a two-sol autonomous 'touch 'n
go' where the rover used the robotic arm (the 'touch') on Sol 3720
(July 11, 2014), to collect a Microscopic Imager mosaic of the
surface target 'Trebia,' followed by an overnight contact integration
measurement performed by the Alpha Particle X-ray Spectrometer
(APXS).

So is the skeptical
explanation of “screw imprint” compatible with this history of
what the Opportunity was doing? No, it is not. The record above
makes clear that the chronology was as follows:

First, during the
Martian day of Sol 3720 (July 11, 2014) the photos at the Trebia
site were taken by the Opportunity rover, including the photo of the
strange-looking “Celtic cross.”

Then, during the
following Martian NIGHT (as indicated by the word “overnight,”)
the APXS instrument was used (presumably to make some type of
contact with the ground), which was the only time that instrument
was used to make contact with the ground during the period between
July 9th and July 17th.

This chronology is completely
incompatible with the skeptical explanation that this “Celtic
cross” was produced by some kind of “screw imprint” caused by
the APXS instrument on the Opportunity rover. If the APXS use had
occurred at this “Trebia” site before the photos were
taken during the day of Sol 3720, such an explanation might be
tenable. But the chronology makes clear that the APXS instrument was
not used at this location until after the photos were taken
that include the “Celtic cross.”

So the official NASA
chronology refutes the glib “screw imprint” explanation for the
“Celtic cross” on Mars. Apparently the mysterious “Celtic
cross” could not have been produced by the APXS instrument.

We are stuck with a big
mystery. What in blazes is an X shape within a perfect circle doing
on the planet Mars? In my next blog post, I will theorize about
several possible explanations for this Martian surface anomaly and
other strange anomalies on the Martian surface. These
explanations will involve various awe-inspiring possibilities.

Postscript: If you read the Opportunity activity log here (the same link given above), it becomes clear that it is something like standard operating procedure for the Opportunity rover to travel to a spot, use the Microscopic Imager unit first to take pictures (the unit that took the "Celtic cross" picture), and then later (usually overnight) to use the APXS instrument (the unit claimed as the source of the "screw imprint") on the same spot. It's easy to see why that order is preferred. Since the APXS has to make contact with the surface, it's better to take the pictures first, to capture the natural, undisturbed look of the soil and rocks being studied (rather than take pictures of the soil after it has been touched and zapped by the APXS with its x-rays and alpha particles).

Copyright Notice

All posts on this blog are authored by Mark Mahin, and are protected by copyright. Copyright 2013-2014 by Mark Mahin. All rights reserved. Any resemblance between any fictional character and any real person is purely coincidental.